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•opy 1 VITED STATES DEPARTMENT OF AGRICULTURE 

BULLETIN No. 839 

Contribution from the Bureau of Chemistry 
CARL L. ALSBERG, Chief 


Washington, D. C. Issued April 23, 1920; revised August, 1922 


THE MICROSCOPICAL EXAMINATION 

OF FLOUR 




/ By 

/ 

GEORGE L.'KEENAN, Microanalyst, and 
MARY A. LYONS, Microanalyst, Microchemical Laboratory 


CONTENTS 


Page 


Review of Literature. 1 

Purpose of Investigation. 3 

Microscopical Method. 3 

Sources of Variation in Method . ... 5 

Examination of Mill Stocks.11 


Page 

Examination of Commercial Grades of 

Flour.16 

Examination of Experimental Series of 

Flour.29 

Summary.31 

Bibliography.32 



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WASHINGTON 

GOVERNMENT PRINTING OFFICE 
1922 


































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UNITED STATES DEPARTMENT OF AGRICULTURE 



BULLETIN No. 839 

Contribution from the Bureau of Chemistry 
CARL L. ALSBERG, Chief 



Washington, D. C. 


Issued April 23, 1920; revised August, 1922 


MICROSCOPICAL EXAMINATION OF FLOUR. 


By George L. Keenan, Microanalyst, and Mary A. Lyons, Microanalyst , 
. Microchemical Laboratory . 

rx^v 

I Z. & CONTENTS. 


Page. 


Review of literature. 1 

P urpose of in vestigation. 3 

Microscopical method. 3 

Sources of variation in method. 5 

Examination of mill stocks. 11 


Page. 


Examination of commercial grades of flour... 16 

Examination of experimental series of flour. 29 

Summary. 31 

Bibliography. 32 


REVIEW OF LITERATURE. 

A review of the literature has shown very few methods for the 
microscopical examination of flours. In the great majority of the 
methods found, suggestions are offered for the separation of the 
wheat tissues from the starch material and the subsequent examina¬ 
tion of the offal under the microscope. The results obtained from 
such microscopical examination, however, are only roughly indicative 
of the offal that may.be present. 

The work of Delaye (5) 1 was concerned largely with the detection 
of foreign spores in flour and also with the presence of ergot. Girard 
(7) suggested the separation of the gluten from the starch and im¬ 
purities by forming the flour into a cake and washing it with running 
water. The starch and impurities were separated with a fine sieve, 
and the offal particles examined under the microscope. Kraemer 
(11) has offered a quantitative method for the examination of com¬ 
mercial flours by means of the microscope, this quantitative method 
to be preceded by a general qualitative examination. A small por¬ 
tion of the flour was weighed out,, a few drops of a reagent added, 
and the number of typical starch grains or characteristic tissues 
enumerated in examining five different portions of the microscop¬ 
ical mount. Standard samples were employed for purposes of com- 

1 The numbers in parenthesis refer to the bibliography on page 32. 

112350°—22—Bull. 839-1 






















2 BULLETIN 839, U. S. DEPARTMENT OF AGRICULTURE. 

parison. As a rule, not less than 12 microscopical mounts were 
made of the standard and of the sample under examination. 

Kohn (10) weighed out one-half gram of the flour, and added 10 
cubic centimeters of ether, shaking the mixture, to isolate the hairs 
and bran tissues which were subsequently identified under the 
microscope. 

Dedrick (4) placed the flour in question upon a glass, and exam¬ 
ined it for offal particles, either with the naked eye or by means of a 
powerful magnifier. Particles of bran, germ, or other impurities 
or substances differing from flour were enumerated, five and six 
trials being made and an average struck. In this way he attempted 
to differentiate between the so-called patent, straight, clear, break, 
and low-grade flours. 

Collin (3) considered the microscopical examination of flour quite 
extensively, although he did not take up the question from the stand¬ 
point of determining the relative amount of offal material present. 
The histology of the wheat grain is fully discussed and illustrated 
with a number of figures. 

Von Liebermann and Andriska (22) suggested a method for esti¬ 
mating the quality of wheat flour which might possibly be correlated 
with a microscopical examination. The quality of the flour with 
respect to the quantity of bran substance present was ascertained 
by shaking the flour with chloroform, and observing the color of 
the portion which floated on the surface. The test might be rendered 
quantitative in the following manner: One gram of the flour was 
shaken in a tube with 10 cubic centimeters of chloroform, and the 
mixture allowed to stand for one hour. The depth of color of the 
layer which then formed on the surface of the chloroform was com¬ 
pared with the colors of the layers produced when mixtures of finest 
white flours and variable portions of bran were subjected to similar 
treatment. These mixtures might contain quantities of washed bran 
ranging from 0 to 2 per cent. The colors of the layers were to be 
observed from above. 

In connection with the work done by Moore and Wilson (15), Pat¬ 
terson has made a microscopical examination of the flour streams 
from the different machines of the mill, these streams being blended 
to form various finished flours. Finished flours were also examined. 
His method consisted in weighing out 3 milligrams (0.003 gram) of 
flour, dividing this into five portions on as many microscopic slides, 
wetting with water, covering with cover slips, and then counting 
under the microscope the number of hairs and epicarp and seed- 
coat particles in the five slides. His results tended to show how 
these particles increased in number in streams from the lower-grade 
machines and were practically absent from those from the “top” 
of the mill. 


MICROSCOPICAL EXAMINATION OF FLOUR. 3 

PURPOSE OF INVESTIGATION. 

From the review of the literature, it is apparent that heretofore 
the purpose of the microscopical examination of flour has usually 
been to determine the presence of adulterants, such as other flours, 
or even starches, spores, etc. The paper in which Patterson indi¬ 
cated the possibilities of an estimation of the offal content of a flour 
microscopically (15) suggested the work here reported. 

MICROSCOPICAL METHOD. 

For convenience, the microscopical method employed in this inves¬ 
tigation will he described under the following headings: (1) Appa¬ 
ratus, (2) technique, and (3) counting bran particles and hairs. 

APPARATUS. 

1. Microscopic slide with a ruled area about 22 millimeters square. 
The lines, which it is convenient to have about 4 millimeter apart, are 
ruled across the short diameter of the slide. 

2. Cover glasses 22 millimeters square. 

3. Compound microscope, with compensating ocular 12 X and 16 
mm. apochromatic objective. 

4. Scalpel, preparation needles, earners-hair brush, spatula, alco¬ 
hol lamp, mechanical stage. 

5. Assay balance. 

6. Chloral hydrate solution about 1:1; preferably not any more 
concentrated. 

TECHNIQUE. 

Before undertaking the examination of a flour microscopically, the 
sample should be thoroughly mixed, and a composite sample with¬ 
drawn from various parts of the material. A 5-milligram portion of 
flour is carefully weighed out upon accurate balances, and the weighed 
portion transferred to the center of the ruled area on the microscopic 
slide. The scalpel is employed in removing flour from the weigh¬ 
ing pan to the slide, the small amount which can not be thus re-, 
moved being easily brushed onto the slide with the cameFs-hair brush. 
The flour being transferred to the slide, about 3 or 4 drops of chloral 
hydrate solution are mixed with the flour by means of the preparation 
needle. Add only enough chloral hydrate solution to fill the space be¬ 
neath the cover glass. The proper amount is usually about 4 drops 
when a pipette with a 1-millimeter bore is employed. A pipette of 
larger bore releases too much solution at a time and is less convenient 
to control. It is important that the material be evenly distributed in 
the solution; otherwise flocculation of the flour will occur, rendering 
counting more difficult and less accurate. The square cover glass is 
next applied, and the slide heated over the alcohol flame until the 


4 


BULLETIN 839, U. S. DEPARTMENT OF AGRICULTURE. 


starch grains are dissolved, or the preparation “cleared,” as is com¬ 
monly stated. Vigorous heating of the slide is to be avoided in order 
to prevent burning of the material before the preparation has been 
sufficiently cleared. After gentle heating, the slide is quickly trans¬ 
ferred to the stage of the microscope, where it is allowed to remain a 
short time before counting is begun. The cold stage causes the larger 
part of the air bubbles that may be present in the preparation to dis¬ 
appear, the very few that remain not hindering in the enumeration 
of the bran particles and hairs. 

Careful adherence to the details of this technique is necessary to 
insure a suitable slide for counting. If a slide is improperly prepared, 
the resulting count probably will not be representative of the flour 
under consideration. 

COUNTING BRAN PARTICLES AND HAIRS. 

A thorough acquaintance with the histology of the wheat grain is 
essential before attempting an examination of flours. Any standard 
work on microscopy or plant anatomy of the common food products 
contains adequate descriptions of the tissues of the wheat bercy in 
various sections. The following brief description of the anatomy of 
the Wheat berry 1 is given for the purpose of indicating the tissues 
which are depended upon for judging a flour with respect to its offal 
content. 

The wheat grain is, botanically, the fruit of various subspecies and 
varieties of the genus Triticum. This grain or fruit consists of a 
series of tissue systems, the outermost of which is the pericarp which 
is composed of three layers, the epicarp, mesocarp, and endocarp. 
The pericarp is essentially the fruit coat or matured ovary wall. 
Within the pericarp is the testa (or spermoderm), rather yellowish- 
brown in color, and easily distinguished in either cross or surface 
sections under the microscope. Within the testa is a layer of rectan¬ 
gular cells (in transverse section) known as the aleurone layer, contain¬ 
ing protein material but no starch. This is essentially the outer layer 
of the endosperm or albumen of the seed. The remainder of the grain 
within the aleurone layer consists of very thin-walled parenchymatous 
cells packed full of starch grains. The small embryo, or germ, is 
located at the end opposite the bearded apex. A crease or groove 
passes longitudinally from the base of the grain to the apex. 

The essential purpose of milling is to produce the finely ground 
endosperm or starchy portion of the wheat grain as free as possible 
from bran particles, hairs, and germ tissues. These bran particles, 
hairs, and germ tissues are known as offal in milling terminology. The 
wheat offal, therefore, consists primarily of all the tissue elements of 


1 A. L. Winton. The Microscopy of Vegetable Foods, 2d ed., pp. 65-73. 1916. 



MICROSCOPICAL EXAMINATION OF FLOUR. 5 

the grain from, and including, the aleurone layer outward, and also 
the germ tissues. Botanically, the 4 bran consists of the pericarp, or 
fruit coat, and the aleurone layer. 

In order to discover any relation that might exist between the bran 
particles and hairs and the various so-called grades of flour, the 
microscopical method already partially described (page 3) was em¬ 
ployed to determine the number of bran particles and hairs ordinarily 
found, in varying amounts, in different classes of flours. This enu¬ 
meration consisted in methodically examining and recording all of the 
bran particles and hairs contained in any given slide. It is well to 
form the habit of always starting at the same point in the mount, 
as, for example, the lower right-hand corner of the slide. The slide is 
slowdy moved by means of the mechanical stage, and all of the bran 
particles and hairs detected outside the edge of the cover slip counted. 
Each particle of spermoderm (with accompanying aleurone layer, if 
present), epicarp, cross-cell and intermediate-cell tissues, and hairs 
are given a value of one, no matter how small the particle or hair 
fragment may be, surface as well as transverse sections being included. 
After the region outside the cover slip is carefully scrutinized, the 
slide is moved over the width of the space between the ruled lines, 
and another strip of the mount examined and the offal 1 counted. A 
bran particle with hairs attached is counted as so many hairs instead of 
being recorded, for the sake of convention, with the bran particle 
count. Germ tissues were not enumerated. This procedure, as de¬ 
scribed, is methodically followed until the entire slide has been 
examined. 

SOURCES OF VARIATION IN METHOD. 

In order to study the reliability of the method aside from its practi¬ 
cal application to the examination of flour, a large number of tests 
were made having for their principal purpose the determination of the 
probable sources of variation and their extent. In considering this 
question it was recognized that there might be a variation due to one 
or all of the following factors: (1) Personal equation, including one 
analyst’s variation in counting the same slide on different days and the 
variation between two analysts counting the same slide on the same 
day; (2) daily variation due to the condition of light, etc.; (3) slide 
variation due to limits of accurate weighing of the test portion of 
flour; and (4) the variation in homogeneity of the bulk sample. 

i For the purpose of this investigation bran particles and hairs were considered as constituting tide 
oflah 





6 


BULLETIN 839, U. S. DEPARTMENT OF AGRICULTURE. 


PERSONAL EQUATION VARIATION. 

COUNTING THE SAME SLIDES ON DIFFERENT DAYS BY ONE ANALYST. 

Table 1 gives actual data obtained from counts made by each of 
two analysts working upon three slides which were prepared from the 
same bulk sample and upon which they made two counts on each of 
three successive days. 

Table 1 . — Results of counts of same slides by two analysts on different days. 


Date. 

' 

Slide. 

Analyst. 

Count 

No. 

Bran 

particles. 

Hairs. 

Total. 

1918. 
Jan. 7 

A 

Keenan. 

1 

87 

59 

146 

Do.. 

A 

.do. 

2 

92 

64 

156 

Do.. 

B 

.do. 

1 

60 

60 

120 

Do.. 

B 

.do. 

2 

60 

58 

118 

Do.. 

C 

.do. 

1 

87 

62 

149 

Do.. 

C 

.do. 

2 

81 

74 

155 

Do.. 

A 

Lyons. 

1 

103 

58 

161 

Do.. 

A 

.do. 

2 

114 

52 

166 

Do.. 

B 

.do. 

1 

86 

64 

150 

Do.. 

B 

.do.'.. 

2 

80 

58 

138 

Do.. 

C 

.do. 

1 

90 

62 

152 

Do.. 

C 

.do. 

2 

87 

57 

144 

Jan. 8 

A 

Keenan. 

1 

76 

66 

142 

Do.. 

A 

.do. 

2 

82 

69 

151 

Do.. 

B 

.do. 

1 

60 

55 

115 

Do.. 

B 

.do. 

2 

49 

48 

97 

Do.. 

C 

.do. 

1 

62 

66 

128 

Do.. 

C 

.do.. 

2 

64 

68 

132 

Do.. 

A 

Lyons.. 

1 

100 

54 

154 

Do.. 

A 

.do. 

2 

96 

56 

152 

Do.. 

B 

.do. 

1 

85 

52 

137 

Do.. 

B 


2 

77 

55 

132 

Do.. 

C 

.do. 

1 

89 

65 

154 

Do.. 

C 

.do. 

2 

83 

59 

142 

Jan. 9 

A 

Keenan. 

1 

80 

65 

145 

Do.. 

A 

.do.. 

2 

83 

66 

149 

Do.. 

B 

.do. 

1 

49 

61 

110 

Do.. 

B 

.do. 

2 

53 

57 

no 

Do.. 

C 

.do. 

1 

60 

66 

126 

Do.. 

C 

.do.•. 

2 

77 

71 

148 

Do.. 

A 

Lyons. 

1 

104 

54 

158 

Do.. 

A 

.do. 

2 

106 

55 

161 

Do.. 

B 

.do. 

1 

78 

55 

133 

Do.. 

B 

.do. 

2 

77 

55 

132 

Do.. 

C 

.do. 

1 

86 

65 

151 

Do.. 

C 

.do. 

2 

86 

62 

148 


For the purpose of emphasizing certain salient points, the results 
recorded in Table 1 have been rearranged in Table 2, in considering 
which it is necessary to regard the different portions carefully. 
Keenan’s greatest variation in two counts of bran particles on a 
given slide on any one day was 17 points (slide C, Jan. 9, 1918), 
while Lyons’ greatest variation was 11 points (slide A, Jan. 7, 1918). 
In the matter of counting hairs the greatest variation in the counts 
obtained on a given slide on any one day by Keenan was 12 points 
(slide C, Jan. 7, 1918), while Lyons’ greatest similar variation was 6 
(in several instances). In these cases it appears therefore that the 
personal variation due to the error of counting probably would not 
exceed 17 points in the case of particles or 12 points in the case of 
hairs. 














































































MICROSCOPICAL EXAMINATION OF FLOUR. 


7 


Table 2. — Variation in counting of each analyst. 


Slide. 

Count 

No. 

Bran particles. 


Hairs. 


Jan. 7, 
1918. 

Jan. 8, 
1918. 

Jan. 9, 
1918. 

Jan. 7, 
1918. 

Jan. 8, 
1918. 

Jan. 9, 
1918. 

A. 

Keenan. 

1 

87 

76 

80 

59 

66 

65 

A. 

2 

92 

82 

83 

64 

69 

. 66 

B. 

1 

60 

60 

49 

60 

55 

61 

B. 

2 

60 

49 

53 

58 

48 

57 

C. 

1 

87 

62 

60 

62 

66 

66 

C. 

2 

81 

64 

77 

74 

68 

71 

A. 

Lyons. 

1 

103 

100 

104 

58 

54 

54 

A. 

2 

114 

96 

106 

52 

56 

55 

B. 

1 

86 

85 

78 

64 

52 

55 

B. 

2 

80 

77 

77 

58 

55 

55 

C. 

1 

90 

89 

86 

62 

65 

65 

C. 

2 

87 

83 

86 

59 

62 

63 


COUNTING THE SAME SLIDE ON THE SAME DAY BY TWO ANALYSTS. 

The variation between the counts made by two analysts on the 
same slide on the same day is demonstrated by comparing the daily 
averages 1 obtained by each of the two analysts. These data are 
compiled in Table 3. 


Table 3. — Variation in counting of two analysts on same day. 


Date. 

Analyst. 

Bran particles. 


Hairs. 


Slide A. 

Slide B. 

Slide C. 

Slide A. 

Slide B. 

Slide C. 

1918. 

| Keenan. 

89 

60 

84 

61 

59 

68 

Jan. 7 

myons. 

108 

83 

88 

55 

61 

59 


[Variation. 

19 

23 

4 

6 

2 

9 


(Keenan. 

79 

54 

63 

67 

51 

67 

Jan. 8 

^ Lyons. 

98 

81 

86 

55 

53 

62 


(Variation. 

19 

27 

23 

12 

2 

5 


(Keenan. 

81 

51 

68 

65 

59 

68 

Jan. 9 

•{Lyons. 

105 

77 

26 

86 

54 

55 

63 


(Variation. 

24 

18 

11 

4 

5 


The table shows an average variation in the count of bran par¬ 
ticles of 20, with a range of from 4 to 27. The average variation in 
the count of hairs was 18, with a range of from 2 to 12. It is evident 
that the variation between analysts in making the count of bran 
particles is greater than in making the count on hairs. 

DAILY VARIATION DUE TO CONDITION OF LIGHT, ETC. 

To determine what influence, if any, physical conditions, such as 
degree of light, have upon the count, it is necessary to first eliminate, 
as far as possible, the personal variations already considered. This 
may be accomplished by taking the average of two counts on three 

1 By “ daily average” is meant the average of two counts made by the same analyst on the same slide 
on a given day. 


































































8 


BULLETIN 839, U. S. DEPARTMENT OF AGRICULTURE. 


slides for the same day and averaging the three results to determine 
the analyst’s daily variation. This is calculated for each analyst. 
The ultimate daily variation is the average of the daily variation of 
the two analysts computed for each day. The daily variation for 
each analyst is shown in Table 4. 


Table 4. —Daily variation for each analyst. 


Slide. 

Variation. 

Bran particles. 

Hairs. 

Jan. 7, 
1918. 

Jan. 8, 
1918. 

Jan. 9, 
1918. 

Jan. 7, 
1918. 

Jan. 8, 
1918. 

Jan. 9, 
1918. 


Keenan. 







A. 


89 

79 

81 

61 

67 

65 

B. 


60 

54 

51 

59 

51 

59 

C. 


84 

63 

68 

68 

67 

68 


Analyst’s daily. 

77 

65 

66 

62 

61 

64 


Lyons. 







A. 


108 

98 

105 

55 

55 

54 

B. 


83 

81 

77 

61 

53 

55 

C. 


88 

86 

86 

59 

62 

63 


Analyst’s daily. 

93 

88 

86 

58 

56 

57 


Ultimate daily. 

85 

76 

76 

60 

63 

60 


The results in Table 4 seem to indicate that on January 7, 1918, 
there was a tendency to count higher on bran particles than on the 
other days. It is believed, however, that this was in whole or in part 
due to the clearing action of the glycerin employed to preserve the 
slides for counting on subsequent days, which tended to make the 
identification of the bran particles more difficult after the first day. 

SLIDE VARIATION DUE TO LIMITS OF ACCURATE WEIGHING OF THE TEST PORTION 

OF FLOUR. 

In order to determine the absolute variation between the slides, 
it is evident that an average must be obtained from which the personal 
variations and the daily variations have been eliminated as far as 
possible. This is accomplished by computing for each slide the aver¬ 
age of all counts made on bran particles, and also making a similar 
computation for the hair count (Table 5). 


Table 5. —Counts of bran particles and hairs on slides. 


Bran particles. 

Hairs. 

Slide A. 

Slide B. 

Slide C. 

Slide A. 

Slide B. 

Slide C. 

89 

60 

84 

61 

59 

68 

79 

54 

63 

67 

51 

67 

81 

51 

68 

65 

59 

68 

108 

83 

88 

55 

61 

59 

98 

81 

86 

55 

53 

62 

105 

77 

86 

54 

55 

63 

i 93 

» 67 

i 79 

i 59 

156 

i 64 


1 Average slide count. 




















































MICROSCOPICAL EXAMINATION OF FLOUR. 


9 


The variation in the counts on these slides naturally raises the ques¬ 
tion of the limits of accuracy in weighing out the test portion of flour. 
Since the amount of flour used on a slide is 5 milligrams, it is desirable 
to determine how great is the error due to weighing the test portion of 
flour. The balance employed in this investigation was a fine assay 
balance. In weighing the sample the vibration method was used, 
and the quantity of flour was so* adjusted as to produce a deviation 
of approximately not more than one-fourth of a space on each side of 
the zero point of the scale. This is equivalent to not more than 1/40 
milligram, or one-half of 1 per cent, on the basis of the portion of flour 
used (5 milligrams). Hence any error in weighing can not he accepted 
as an explanation of the difference in slide counts. 

VARIATION IN HOMOGENEITY OF BULK SAMPLE. 

The question has been raised as to whether or not a portion of the 
slide variation might not he accredited to lack of uniformity of the 
bulk sample, due to the fact that any grade of flour is usually the 
component result of several constituent streams which vary more or 
less among themselves. The fact that in general practice the flour 
stocks are subjected to a certain degree of purification, however, 
leaves this factor little chance to figure to any great extent. This 
point was tested by passing a certain sample of flour which had an 
average count of 32 bran particles and 64 hairs through a 30-mesh 
sieve and making up and counting 12 slides. The bulk sample was 
then passed through the sieve once more (making two times for the 
sample), and another series of slides made and counted. Finally, 
the sample was put through the sieve twice more (making four times 
for the sample), and a third series of 12 slides made and counted. The 
results of these tests are given in Table 6, the counts in which are the 
average of the results obtained by two persons. 

Table 6 . —Effect of variation in homogeneity of sample on count. 


Sample passed through 30-mesh sieve— 

Once. 

Twice. 

Four times. 

Bran 

particles. 

Hairs. 

Bran 

particles. 

Hairs. 

Bran 

particles. 

Hairs. 

31 

73 

26 

67 

21 

76 

48 

73 

37 

70 

22 

53 

36 

58 

25 

58 

30 

56 

33 

53 

22 

54 

32 

81 

41 

64 

27 

61 

23 

79 

36 

64 

32 

57 

29 

66 

35 

74 

32 

83 

36 

60 

35 

75 

27 

64 

34 

56 

37 

57 

34 

61 

39 

70 

35 

76 

26 

72 

38 

52 

30 

66 

39 

67 

33 

65 

34 

60 

30 

67 

37 

48 

135 

166 

i 29 

165 

131 

i 63 

218 

2 23 

217 

2 29 

2 18 

2 31 


i Average. a Variation 


112350°—22—Bull. 839-2 

























10 BULLETIN 839, U. S. DEPARTMENT OF AGRICULTURE. 

Apparently, sifting or thorough mixing of the flour a number of 
times has little appreciable effect upon the offal count obtained. 

NUMBER OF SLIDES COUNTED. 

In practice, two slides, or at most three, from the sample of flour 
have been used as the basis for judgment as to the character of the 
product as far as the offal material was concerned, and the question 
might very properly be asked if that number is sufficient. In order 
to test out this point, 12 slides were prepared from the same bulk 
sample of flour. Two counts on each slide were made of the bran 
particles and hairs by each of two analysts. The results obtained are 
recorded in Table 7. 

Table 7. —Counts on 12 slides. 


Slide des¬ 
ignation. 

Analyst. 

Count 

No. 

Bran 

parti¬ 

cles. 

Hairs. 

Slide des¬ 
ignation. 

Analyst. 

Count 

No. 

Bran 

parti¬ 

cles. 

Hairs. 

A. 

Keenan. 

1 

21 

76 

G. 

Keenan. 

1 

38 

64 

A. 

_do. 

2 

22 

75 

G. 

.do. 

2 

32 

57 

A... 

Lyons. 

1 

20 

78 

G. 

Lyons. 

1 

35 

61 

A. 

. 7 . .do. 

2 

22 

77 

G. 

.. 7. .do. 

2 

40 

61 

B. 

Keenan. 

1 

24 

54 

H. 

Keenan. 

1 

37 

61 

B. 

_do. 

2 

23 

53 

H. 

_ do. 

2 

24 

47 

B. 

Lyons. 

1 

19 

52 

H. 

Lyons_ 

1 

38 

56 

B. 


2 

23 

56 

H. 

. .do. 

2 

40 

61 

C. 

Keenan. 

1 

23 

55 

I. 

Keenan. 

1 

26 

74 

C. 

.do. 

2 

31 

60 

I. 

.do..*. 

2 

44 

67 

C. 

Lyons. 

1 

34 

59 

I. 

Lyons. 

1 

44 

67 

C. 

.. 7 . .do. 

2 

33 

53 

I. 

.. 7. .do. 

2 

42 

72 

D. 

Keenan. 

1 

33 

77 

J. 

Keenan. 

1 

39 

50 

D. 

. ...do. 

2 

30 

81 

J. 

.do. 

2 

38 

55 

D. 

Lyons. 

1 

31 

84 

J. 

Lyons. 

1 

34 

48 

D. 

... .do. 

2 

35 

82 

J. 


2 

41 

56 

E. 

Keenan. 

1 

24 

79 

K. 

Keenan. 

1 

32 

63 

E. 

.do. 

2 

22 

79 

K. 

.do. 

2 

30 

60 

E. 

Lyons. 

1 

23 

82 

K. 

Lyons. 

1 

33 

68 

E. 

..". .do. 

2 

26 

78 

K. 


2 

37 

71 

F. 

Keenan. 

1 

31 

64 

L. 

Keenan. 

1 

32 

47 

F. 

.. ..do. 

2 

29 

65 

L. 

. .do. 

2 

36 

49 

F.... 

Lyons. 

1 

29 

70 

L. 

Lyons. 

1 

42 

47 

F. 


2 

30 

66 

L_ 

7 do_ 

2 

39 

51 






1 




From the data in Table 7 it is-possible to average Keenan’s first 
count on slide A with each count made by him on each of the other 
slides. By averaging the slides by two, 20 is found to be the lowest 
average and 43 the highest average for bran particles, considering 
Keenan’s results only. If the average of counts for three slides 
instead of two is to be taken as the basis for final judgment of the 
product, it is apparent that 22 is the average of the three lowest 
results and 40 the average of the three highest (Keenan’s results on 
bran particles). Taking the average of the counts on each of four 
slides gives an average minimum count of 22 and an average maximum 
count of 39. Table 8, based on data obtained from Table 7, has 
been prepared to show the results of such methods of grouping. 






















































































































MICROSCOPICAL EXAMINATION OF FLOUR. 


11 


Table 8. —Effect of method of computing average on count. 


Method of averaging. 

• 

Bran particles. 

Hairs. 

Keenan. 

Lyons. 

Keenan. 

Lyons. 

Min. 

Max. 

Min. 

Max. 

Min. 

Max. 

Min. 

Max. 

Bv twos. 

20 

43 

19 

43 

48 

80 

49 

83 

By threes. 

22 

40 

20 

42 

47 

79 

48 

81 

By fours. 

22 

39 

21 

41 

49 

79 

49 

81 

By fives. 

23 

39 

21 

41 

51 

77 

50 

80 


EXAMINATION OF MILL STOCKS. 1 

Before undertaking a discussion of the work done on finished com¬ 
mercial flours, it seemed advisable to consider the degree of purity of 
the various mill stocks entering into the composition of the end- 
product. The data compiled in Table 9 demonstrate the quality of 
the stocks made on the break rolls, the purpose of which is to crush 
the wheat kernel to release the enclosed endosperm that is later re¬ 
duced to fineness on other rolls and finally purified of offal debris. 
The general practice in milling is to make as little break flour as possi¬ 
ble. When break flour is made to any extent, it invariably con¬ 
tains a notable amount of offal, consisting of bran particles, as well 
as numerous hairs from the beard. The results recorded in Table 9 
were obtained on samples of material procured from the first, second, 
third, and fourth break rolls, respectively, and from different mills. 
It was stated that they had been bolted through silks of various 
numbers of meshes per lineal inch, the following silks being employed: 


Silk number. 

Meshes 
per inch. 

lOxx. 

109 

llxx. 

116 

12xx. 

125 

12x. 

125 

12xxx. 

125 

13xx. 

129 

14xxx. 

139 



1 The designations for the various stocks and grades of flour examined, as well as the statements concern¬ 
ing the kind of wheat from which the flour was milled, were taken from the millers supplying the samples 
and were not verified in the Bureau of Chemistry. 








































12 


BULLETIN 839, U. S. DEPARTMENT OF AGRICULTURE. 

Table 9. —Results of examination of products from break machines. 


Sample No. 

Type of wheat. 

Bolting cloth. 

Bran 

particles. 

Hairs. 

Total. 

11079-Iv-A. 

Hard. 

FIRST BREAK MATERIAL. 

(?). 

196 

165 

361 

17146-L-B. 

. ..do. 

il'xx, 13xx. 

186 

83 

269 

17125-L-C. 

Hard and soft.. 

(?). 

117 

43 

160 

17128-L-A. 

.do. 

(?). 

334 

162 

496 

17159-L-A. 

. .do. 

(?). 

76 

61 

137 

17173-L-A. 

.do. 

(?). 

46 

64 

110 

17165-L-O. 

Soft. 

io'xx. 

113 

38 

151 

17167-L-A. 

.do. 

12xxx, 14xxx. 

182 

58 

240 

17143-L-B. 

Hard. 

SECOND BREAK MATERIAL. 

lOx, llx. 

324 

42 

366 

17146-L-A.. 

. .do.. 

12xx, 13xx. 

166 

65 

231 

17190- L-B. 

do. 

12xx, 13xx. 

216 

162 

378 

17125-L-D. 

Hard and soft. 

(?)..'. 

105 

23 

128 

17128-L-C. 

. ..do. 

(?). 

150 

83 

233 

17159-L-B. 

.do. 

(?).. 

47 

44 

91 

17173-L-B. 

_do. 

(?). 

32 

54 

86 

17133-L-F. 

Soft. 

(?). 

142 

58 

200 

17165-L-P. 

. .do. 

10xx. 

75 

38 

113 

17167-L-B. 

.do. 

12xxx, 14xxx. 

138 

31 

169 

11079-K-D. 

Hard. 

THIRD BREAK MATERIAL. 

(?). 

120 

121 

241 

17143-L-C. 

.do. 

iOx, llx. 

628 

107 

735 

17146-L-D. 

.do. 

12xx, 13xx. 

367 

144 

511 

17125-L-E. 

Hard and soft. 

(?)..'. 

159 

26 

185 

17128-L-D. 

.do. 

(?). 

118 

53 

171 

17159-L-C. 

_do. 

(?).. 

68 

60 

128 

17173-L-C. 


(?).:. 

37 

56 

93 

17133-L-G. 

Soft. 

(?). 

375 

73 

448 

17165-L-Q. 

.do. 

iOxx. 

131 

53 

184 

17167-L-C_ 

.do. 

12xxx, 14xxx. 

135 

46 

181 

17143-L-D. 

Hard. 

FOURTH BREAK MATERIAL. 

llx, 12x... 

810 

213 

1,023 

438 

319 

168 

279 

334 

351 

17146-L-C. 

.. ..do. 

12xx, 13xx. 

322 

116 

17125-L-F. 

Hard and soft. 

(?)..'.-.. 

262 

57 

17128-L-E. 

.do.. 

(?). 

118 

50 

17173-L-D. 

.do. 

(?). 

132 

147 

17165-L-R. 

Soft. 

IOxx. 

228 

106 

17167-L-D. 

.do. 

14xxx. 

285 

66 


--- 



For the purpose of comparison, the data from Table 9 have been 
summarized in Table 10. 

Table 10. —Summary of results of examination of products from break, machines.. 


Machine stock. 

Aver 

Bran 

particles. 

age. 1 

Hairs. 

First break. 

156 

84 

Second break. 

139 

60 

Third break. 

213 

73 

Fourth break. 

308 

122 


1 Throughout this bulletin averages are expressed in whole numbers, decimals being disregarded and 
the lower rather than the higher figure being used in each instance. 

The offal content of the break roll products is high, as would be 
expected. A microscopical examination is hardly necessary to estab¬ 
lish this fact. The fluffy and dirty appearance of such products, 
even from casual examination, is sufficient to show that they are of 
low quality, judging from the offal material present. 

































































































































MICROSCOPICAL EXAMINATION OF FLOUR 


13 


Tests similar to those made on break roll products were made 
on middlings stock. Middlings are usually recognized as being the 
medium granular particles of the endosperm resulting from the crack¬ 
ing of the wheat kernel on the break rolls. After proper purification 
or removal of the branny material, the middlings are milled, on the 
reduction rolls, to the fineness of flour. The results of experimental 
work done on middlings stocks are recorded in Table 11. 


Table 11. —Results of examination of middlings stocks. 


Sample No. 

Type of wheat. 

Bolting cloth. 

Bran 

particles. 

Hairs. 

Total. 


• 


FIRST MIDDLINGS STOCK. 




15196-K-E... 

Hard. 

lOxx, llxx, 12xx. 

22 

18 

40 

17144-L-I. 

.do. 

10x..'. 

14 

4 

18 

17190-L-I.. 

. .do. 

lOxx. 

36 

16 

52 

17125-L-L. 

Hard and soft. 

m__ 

23 

2 

25 

17159-Lr-F. 

.. .do. 



18 

22 

40 

17132-L-J. 

Soft. 

(?). 

19 

3 

22 

17133-L-L. 

.do. 

(?). 

59 

12 

71 

17165-L-B. 

.do. 

lOxx. 

21 

8 

29 

17185-L-C.... 

.do. 

lOxx__ 

5 

2 

7 




SECOND MIDDLINGS STOCK. 




15196-K-C 

Hard. 

12xx, 13xx, 14xx. 

5 

3 

8 

17144-L-J_ 

.. .do. 

10x..'..'. 

7 

3 

10 

17146-L-G 

.do. 

llxx, 12xx. 

29 

2 

31 

17190-L-I.. 

.do. 

llxx'... 

100 

50 

150 

17125- L-N. 

Hard and soft. 


?). 

11 

1 

12 

17159-L-G 

.do. 


?). 

7 

5 

12 

17132-L-K .. 

Soft . 


?). 

25 

1 

26 

17133-L-O. 

. .do. 


?). 

59 

6 

65 

17165-L-C . 

.do. 


lOxx.. 

48 

27 

75 

17185-L-D. 

.do. 

lOxx.... 

8 

4 

12 




THIRD MIDDLINGS STOCK. 



17144-L-K . 

TTard. 

lOx, llx. 

8 

1 

9 

17146-L-I 

do. 

llx, 12xx. 

27 

6 

33 

17190-L-J 

do. 

lOxx, llxx. 

14 

5 

19 

17125- L-P 

Hard and soft. 

(?)..'. 

6 

3 

9 

17128-L-K . 

do. 

m.. 

69 

26 

95 

17159-L-H 

do. 


?). 

19 

22 

41 

17173-L-0 

do. 


>?). 

18 

24 

42 

17132.-L-L. 

Soft.. 


H.. 

9 

0 

9 

17133-L-O 

.do. 

(?). 

34 

5 

39 

17165-L-D. 

.do. 

lOxx. 

36 

7 

43 

17167-L-J_ 

do. 

14xxx. 

21 

5 

26 

17185-L-F. 

. .do. 

lOxx.. 

9 

4 

13 




FOURTH MIDDLINGS STOCK. 




15196—K—J 

TT ard. 

llxx, 12xx, 14xx. 

10 

6 

16 

17190-L-K 

do. 

llxx^ 12xx. 

76 

25 

101 

17125-L-T 

Hard and soft. 

(?). 

7 

1 

8 

1712ft-L-O 

.do. 

(?). 

38 

23 

61 

17159-L-I 

.do. 

(?). 

8 

10 

18 

17171 L L 

do. 

11xxx. 12xx. 

82 

9 

91 

17132-L M 

Soft . 


'?)...'. 

26 

1 

27 

17133-L-S 

.do. 


>?s.. 

. 26 

5 

31 

17165-L-F 

.do. 

12xx. 

29 

2 

31 

17167-L-M . 

.do. 


'?). 

115 

24 

139 

17167-L-K... 

.do. 


*?). 

40 

6 

46 




FIFTH MIDDLINGS STOCK. 




15196-K-K 

H ard_ _. 

llxx, 12xx, 14xx. 

18 

13 

31 

17144-T. M 

.do. 

10x, ilx...'. 

9 

1 

10 

17146 T,-H 

do. 

llxx, 12xx. 

21 

5 

26 

171Qn_Tj-L 

do.. 

llxx' 12xx. 

74 

22 

96 

1712 ft-L-P 

Hard and soft ...... 


?)..'. 

74 

36 

110 

1715Q T j T 

do . 


?L .. 

10 

9 

19 

17171 L M 

do. 

12xx. 

65 

19 

84 

17173 T>-P 

do... 


?). 

57 

57 

114 

17133 L U 

Soft 


. 

80 

18 

93 

17165-L H 

.do.. 

i2xx. 

55 

12 

67 

17167-L-O. 


(?). 

13 

10 

53 












































































































































































14 


BULLETIN 839, U. S. DEPARTMENT OF AGRICULTURE. 

Table 11 .—Results of examination of middlings stocks —Continued. 


f 


Sample No. 

Type of wheat. 

Bolting cloth. 

Bran 

particles. 

Hairs. 

Total. 



! ' 

SIXTH MIDDLINGS STOCK. 




15196-K-G. 

Hard. 

llxx, 12xx, 13xx, 14xx. 

26 

30 

56 

17144-L-N. . 

.do. 

llx, 12x, 13xx. 

24 

1 

25 

17190- L-M. 

..do. 

llxx, 12xx. 

139 

33 

172 

17125-L-BB ... 

Hard and soft,. 

(?). 

87 

15 

102 

17128-L-Q. 

.do. 

(?). 

70 

37 

107 

17173-L-Q. 

.do. 

(?). 

41 

66 

107 

17173-L-R. . 

.do. 

(?). 

22 

35 

57 

17133-L-W_ 

Soft. 

(?). 

140 

18 

158 

17165- L-I.... 

.do. 

l2xx. 

60 

18 

78 



SEVENTH MIDDLINGS STOCK. 




15196-K-F... * 

Hard . 

12xx, 13xx, 14xx. 

16 

9 

25 

17144-L-O. . 

do. 

12x, 13x. 

36 

4 

40 

17190-L-N... . 

do. 

13xx, 14xx. 

119 

43 

162 

17128-L-R. . 

Hard and soft. 

(?)..'. 

63 

26 

89 

17159-L-M. 

do. 

(?). 

104 

78 

182 

17138-L-X. 

Soft . 

(?). 

194 

16 

210 

17165-L-J. 

. do. 

i2xx, 13xx. 

143 

23 

166 

17167-L-L. 

. .do. 

(?). 

45 

13 

58 



EIGHTH MIDDLINGS STOCK. 




17190-L-O. . 

Hard. 

13xx, 14xx. 

137 

23 

160 

17173-L-S_ 

Hard and soft.. 

(?)./ . 

51 

52 

103 

17165-L-K. 

Soft. 

13xx, 14xx. 

264 

38 

302 



NINTH MIDDLINGS STOCK. 




17167-L-S. 

Soft. . 

(?). 

92 

25 

117 







The average results obtained on the middlings stocks examined 
have been summarized in Table 12. 

Table 12 .—Summary of results of examination of middlings stocks. 


Stock. 


First middlings.... 
Second middlings.. 
Third middlings... 
Fourth middlings. 
Fifth middlings... 
Sixth middlings... 
Seventh middlings 
Eighth middlings.. 
Ninth middlings... 


Average. 

Total. 

Bran 

particles. 

Hairs. 

24 

9 

33 

29 

10 

39 

21 

9 

30 

41 

10 

51 

46 

18 

64 

65 

26 

91 

90 

26 

116 

150 

37 

187 

92 

25 

117 


The results in Table 12 clearly demonstrate that the middlings 
stocks are much cleaner than stocks obtained from the break rolls. 
The first five middlings stocks average low in the total offal count, 
while the stocks from the sixth to ninth middlings, inclusive, average 
appreciably higher. In other words, the more thorough the purifi¬ 
cation process, the lower will be the offal count. 

For the purpose of showing the offal count on the stocks which pass 
into some so-called patent flours, three different sets of mill streams 



































































































MICROSCOPICAL EXAMINATION OF FLOUR. 


15 


were examined, these streams being designated as entering into the 
composition of certain finished flours. The mill streams composing 
such flours were milled from hard, blended, and soft wheats, respec¬ 
tively. The results of these examinations are shown in Tables 13, 
14, and 15. 


Table 13. —Results of examination of mill streams composing a patent flour {sample No. 

17144-L-FF) milled from hard wheat. 


Stock. 

Bran 

particles. 

Hairs. 

Total. 

First middlings. 

14 

4 

18 

Second middlings. 

7 

3 

10 

Third middlings. 

8 

1 

9 

Fourth middlings. 

19 

2 

21 

Fifth middlings^. 

9 

1 

10 

Sixth middlings. 

24 

1 

25 

Seventh middlings. 

36 

4 

40 

Middlings..7.. 

36 

5 

41 

Do.7. 

30 

5 

85 

First sizings. 

59 

8 

67 

Second sizings. 

37 

2 

39 

Sizings.7. 

151 

20 

171 

Finished flour (70 per cent patent)!. 

13 

2 

15 


1 This finished flour is composed of the stocks described above it. 


Table 14. —Results of examination of mill streams composing a patent flour {sample No. 

17159-L-V) milled from blended wheat. 


Stock. 

Bran 

particles. 

Hairs. 

Total. 

First break. 

76 

61 

137 

Second break. 

47 

44 

91 

Third break. 

68 

60 

128 

95 

Break chops. 

41 

54 

Do.. .7. 

56 

84 

140 

40 

First middlings. 

18 

22 

Second middlings. 

7 

5 

12 

41 

18 

Third middlings... 

19 

22 

Fourth middlings. 

8 

10 

Fifth middlings (head). 

10 

9 

19 

Fifth middlings (tail). 

19 

14 

33 

32 

14 

35 

Coarse tailing^.... 

19 

13 

Coarse sizings.„. 

6 

8 

Finished flour (70 per cent patent) i. 

20 

15 



1 This finished flour is composed of the stocks described above it. 


Table 15. — Results of examination of mill streams composing a patent flour {sample No. 

17132-L-U) milled from soft wheat. 


Stock. 

Bran 

particles. 

Hairs. 

Total. 

First middlings. 

19 

3 

22 

Second middlings. 

25 

1 

26 

Third middlings.. 

9 

0 

9 

Fourth middlings. 

26 

1 

27 

Fine sizings. 

10 

1 

11 

Medium sizings. 

21 

2 

23 

Coarse sizings. 

14 

2 

16 

Finished flour (60 per cent patent) 1 . 

19 

1 

20 


• 


1 This finished flour is composed of the stocks described above it. 
































































16 BULLETIN 839, U. S. DEPARTMENT OF AGRICULTURE. 

It is interesting to observe the variety of streams drawn upon for 
the composition of different so-called patents, as well as the varia¬ 
tion in the offal count of the stocks employed in the milling of such 
finished flours. If space permitted, additional information could 
be submitted to-illustrate how variable the different mill stocks are 
as far as offal content is concerned. In many instances where 
lower-grade stocks have been employed in making a flour, however, 
the finished product has usually been purified sufficiently to cause 
the resultant offal count to be appreciably low. And in many cases 
the contrarv is true. 

EXAMINATION OF COMMERCIAL GRADES OF FLOUR. 

The assembled flours employed in this part of the investigation 
were collected by B. C. Winslow, food and drug inspector, Bureau 
of Chemistry, United States Department of Agriculture. As these 
flours were milled under a variety of conditions, they necessarily 
reflect such conditions in the finished product. The inspector gave 
the following statement as to the designations applied to these 
flours: “As a general thing, these names were used in harmony 
with the usage of the mill where they were taken. The method of 
assembling, with the streams, percentages, etc., were given when 
feasible, and as correctly as possible from the information available. 
The general terms 1 patent/ 1 clear/ and ‘straight’ were used to clas¬ 
sify in.a general way the assembled grades of flour, and vary with 
each mill.” 

With this information in mind, an attempt was made to apply the 
microscopical method already described to an examination of these 
products for the purpose of developing a system for the classification 
of flours based on the offal content. A detailed discussion of the 
actual data obtained from these tests, with a general summary on the 
various so-called grades, follows. 

PATENT FLOURS. 

PATENT FLOURS MILLED FROM HARD WHEATS. ’ 

Thirty-six patent flours said to have been milled from hard wheats 
were examined microscopically, and their bran particle and hair 
count determined. The commercial grade designations ranged from 
40 to 94 per cent. In some instances the flour had been bleached; 
in others it was bleached only lightly or not at all. Table 16 gives 
the results of this examination. 


MICROSCOPICAL EXAMINATION OF FLOUR. 


17 


Table 16 .—Results of examination of patent flours milled from hard wheats. 


Sample No. 

Commer¬ 
cial grade. 

Bleachea. 

Bran 

particles. 

Hairs. 

Total. 

15163-K-R. 

“Per cent 
patent.” 
(?) 
(?) 
40 

Yes. 

16 

8 

24 

15178-K-U. 

(?). 

29 

13 

42 

17151-L-MM. 

No. 

19 

13 

32 

17151-L-NN. 

52 

No. 

72 

45 

117 

17150-L-T. 

58* 

60 

No. 

27 

9 

36 

15152-K-A. 

Yes. 

15 

5 

20 

15134-K-EE. 

65 

No. 

24 

20 

44 

11078-K-LL. 

68 

No. 

23 

20 

43 

11078-K-MM. 

68 

Yes. 

22 

15 

37 

11070-K-FF. 

70 

(?). 

22 

21 

43 

15112-K. 

70 

No. 

16 

12 

28 

15113-K. 

70 

Lightly. 

17 

11 

28 

17154-L-AA. 

71 

No...:. 

20 

10 

30 

15174-K-LL . 

72 

(?). 

17 

4 

21 

15187-K-X. 

72 

No. 

27 

14 

41 

15170-K-CC. 

74 

No. 

29 

26 

55 

17144-L-FF. 

74 

No. 

13 

2 

15 

17190-L-CC. 

75 

Yes. 

66 

33 

99 

17143-L-CC. 

75 

No. 

33 

2 

35 

15193-K-EE. 

75 

No. 

33 

36 

69 

15193-K-DD. 

75 

Yes. 

30 

39 

69 

11028-K-B. 

75 

(?). 

19 

13 

32 

17157-L-A . 

77 

Yes... 

25 

24 

49 

17183-L-A . 

78 

No. 

35 

28 

63 

17184-L-Q. 

79 

Yes. 

25 

31 

56 

11064-K-A... . . 

80 

No. 

54 

28 

82 

17175-L-MM. . 

80 

No. 

44 

9 

53 

15181-K-S . 

80 

No. 

17 

19 

36 

171*4 7-L-B B . 

83 

Yes. 

34 

16 

60 

17148-L-MM.. . 

83 

Yes. 

34 

10 

44 

17156-L-FF. . 

83 

Yes.. 

36 

30 

66 

17155-L-JJ. 

84 

No. 

33 

12 

45 

17135-K-CC . 

85 

No. 

32 

23 

55 

17145-L-B . 

85 

No. 

36 

15 

51 

17111-L-S . 

88 

No. 

33 

9 

42 

i7180~L-JJ . 

94 

Yes. 

62 

34 

96 


• 






On these hard-wheat patents the bran particle count ranged from 
15 to 72, with an average of 30. The hair count ranged from 2 to 45, 
with an average of 18. The total offal count ranged from 15 to 117, 
with an average of 45. 


PATENT FLOURS MILLED FROM SOFT WHEATS. 

The patent flours milled from soft wheats are more starchy than 
those milled from hard wheats. This starchy character is manifest 
even when the sample of flour is poured out upon a piece of paper. 
The soft-wheat flour will not “flow” like a flour made from hard 
wheat, but is more “powdery” and starchlike rather than granular, 
as in the case of hard-wheat flours. Thirteen patent flours stated to 
have been milled from soft wheats were examined microscopically. 
As in the case of hard-wheat flours, the commercial grades, as indi¬ 
cated by percentages, varied markedly, and can be regarded only as 
approximate. The percentages ranged from 35 to 90 per cent. 
Some of the flours were bleached, others lightly bleached, and still 
others not bleached at all. Table 17 gives the results of this examina¬ 
tion. 
























































































18 


BULLETIN 839, U. S. DEPARTMENT OF AGRICULTURE. 

Table 17. —Results of examination of patent flours milled from soft wheats. 


Sample No. 

Commer¬ 

cial 

grade. 

Bleached. 

Bran 

particles. 

Hairs. 

Total. 

t 

17161-L-A . 

“Per cent 
patent.” 

(?) 

35 

Yes. 

72 

10 

82 

17189-L-O . 

No. 

32 

25 

57 

17167-L-FF. 

40 

Yes. 

32 

11 

43 

17165-L-EE. 

45 

Yes. 

33 

32 

65 

17132-L-XJ. . 

60 

No. 

19 

1 

20 

17169-L-S . 

60 

(?). 

49 

34 

83 

17187-L-V . 

60 

No. 

23 

17 

40 

15121-K-EE. 

65 

Yes. 

50 

12 

62 

15126- K-FFF. 

65 

Yes. 

56 

22 

78 

17133-L-FF. 

65 

Yes. 

133 

29 

162 

17161-L-LLL. 

67 

No. 

46 

19 

65 

17164-L-T. 

75-80 

(?). 

53 

26 

79 

11007-K. 

90 

(?). 

51 

30 

81 





The bran particle count varied from 19 to 133, the hair count from 
1 to 34, and the total offal count from 20 to 162. The average count 
for bran particles was 49 and that for hairs 20, while the average total 
offal count amounted to 70. 


PATENT FLOURS MILLED FROM BLENDED WHEATS. 

• 

The flours classified under blends were manufactured from mix¬ 
tures of hard and soff wheats. Similar information was obtained for 
these flours as for the hard and soft types. The designations for 
the so-called grades varied from 70 to 85 per cent. Of the 12 sam¬ 
ples examined, 4 were bleached and 8 unbleached. Table 18 gives 
the results. 


Table 18. —Results of examination of patent flours milled from blended wheats. 


Sample No. 


11084-K. 

11085-K. 

11086-K. 

17159-L-V_ 

17171-L-B_ 

17168-L-YS.., 
17168-L-YYH 
17179-L-YY.. 

17127-L-S_ 

17116-L-D_ 

17123-L-FF. . 
17125-L-FF.. 


Commer¬ 

cial 

grade. 

Bleached. 

Bran 

particles. 

Hairs. 

Total. 

“Per cent 





patent.” 

No. 




70 

29 

13 

42 

70 

Lightly..'.. 

32 

13 

45 

70 

Heavily. 

31 

18 

49 

70 

No. 

20 

15 

35 

70 

No. 

51 

25 

76 

75 

No. 

40 

37 

77 

75 

No. 

18 

13 

31 

80 

No. 

36 

19 

55 

82 

No. 

63 

27 

90 

83 

Yes. 

61 

40 

101 

85 

Yes. 

47 

21 

68 

85 

No. 

83 

t 

17 

100 


The bran particle count ranged from 18 to 83, with an average of 
42. The hair count ranged from 13 to 40, with an average of 21. 
The total offal count ranged from 31 to 101, with an average of 64. 



















































































MICROSCOPICAL EXAMINATION OF FLOUR. 


19 


PATENT FLOURS MILLED FROM MIDDLINGS STOCKS ONLY. 


Information was obtained concerning the history of the mill 
streams entering into the composition of a large number of so-called 
patent flours. The data collected showed that middlings stocks only 
were employed in composing these flours. The results of the counts 
made on these samples are recorded in Table 19. 


Table 19 .—Results of examination of patent flours milled from middlings stocks only. 


17151-L-MM 
15152-K-A.. 
11070-K-FF. 
17154-L-AA. 
17158-L-X... 
15186-K-X.. 
15174-K-LL. 
15170-K-CC. 
17144-L-FF. 
15181-K-S... 
15146- K-W.. 


15163-K-R 


Sample No. 


Commer¬ 

cial 

grade. 

Bleached. 

Bran 

particles. 

“Per cent 
'patent.” 
40 

(?). 

19 

60 

Yes. 

15 

70 

(?). 

22 

71 

No. 

20 

71 

Yes. 

19 

•72 

No. 

27 

72 

(?). 

17 

74 

No. 

29 

74 

No. 

13 

80 

Yes. 

17 

Short 

(?). 

28 

patent. 

(?) 

Yes. 

16 



Hairs. 


Total. 


13 

32 

5 

20 

21 

43 

10 

30 

13 

32 

14 

41 

4 

21 

26 

55 

2 

15 

19 

36 

23 

51 


8 


24 


Table 19 shows that the bran particle count ranged from 13 to 29, 
with an average of 20, that the hair count ranged from 2 to 26, with 
an average of 13, and that the total offal count ranged from 15 to 55, 
with an average of 33. These results demonstrate the fact that the 
purified middlings stocks employed had some effect upon the purity of 
the end-product. From the information the writers were able to 
obtain, however, so-called patent flours were not always composed of 
the best streams in the mill. 

PATENT FLOURS MILLED FROM MIDDLINGS STOCKS PLUS LOWER-GRADE STOCKS IN THE 

MILL. 

As already stated, stocks other than first-class middlings were often 
passed into patent flours. According to the information submitted, 
break flours and lower grades of middlings frequently were found to 
have been employed in the manufacture of the finished flour. The 
results recorded in Table 20 illustrate the effect of the addition of 
mill streams appreciably high in offal to the finished product. 




































20 BULLETIN 839, U. S. DEPARTMENT OF AGRICULTURE. 

Table 20 .—Results of examination of patent flours milled from middlings stocks in 

addition to lower-grade stocks in the mill. 


Sample No. 

Com¬ 

mercial 

grade. 

Variety of wheat. 

17189-L-O. 

‘Per cent.” 
35 
52 
60 
65 
67 
70 
70 
75 
75 
75 
75 
75-80 

78 

79 

80 
80 
82 
83 
83 

83 

84 

85 
85 
85 
94 

Soft. 

17151-L-NN *. 

Hard. 

17169-L-S. 

Soft. 

17133-L-FF . 

.do. 

17161-L-LLL. 

.do. 

17159-L-V. 

Blend. 

17171-L-B. 

.do. 

15193-K-DD. 

Hard. 

15193-K-EE. 

.do. 

17190-L-CC. 

.do... 

17168-L-YYH. 

Blend. 

17164-L-T. 

Soft. 

17183-L-A. 

Hard. 

17184-L-Q. 

.do. 

11064-K-A. 

.do. 

17179- L-YY. 

Blend. 

17127-L-S. 

.do. 

17147-L-BB. 

Hard. 

17156-L-FF. 

.do. 

17116-L-D. 

Blend. 

17155-L-JJ. 

Hard. 

17123-L-FF. 

Blend. 

17125-L-FF. 

.do. 

15135-K-CC. 

Hard. 

17180-L-JJ. 

.do. 




Bleached. 

Bran 

particles. 

Hairs. 

Total. 

No. 

32 

25 

57 

No. 

72 

45 

117 

Yes. 

49 

34 

83 

Yes . 

133 

29 

162 

No. 

• 46 

19 

65 

No. 

20 

15 

35 

No. 

51 

25 

76 

Yes.. 

30 

39 

69 

No . 

33 

36 

69 

Yes. 

66 

33 

99 

No. 

18 

13 

31 

Yes. 

53 

26 

79 

No. 

35 

28 

63 

No. 

25 

31 

56 

No. 

54 

28 

82 

No. 

36 

19 

55 

Yes. 

63 

27 

90 

Yes. 

34 

16 

50 

Yes. 

36 

30 

66 

Yes. 

61 

40 

101 

No. 

33 

12 

45 

Yes. 

47 

21 

68 

No. 

83 

17 

100 

No. 

32 

23 

55 

Yes. 

62 

34 

96 



The total offal count on these samples was consistently higher in 
most cases than the results obtained on samples ground from mid¬ 
dlings stock only. The addition of break flour stocks appeared to 
have a marked effect upon their quality with respect to the offal 
count. The bran particles ranged in count from 18 to 133, with an 
average of 48. The hair count ranged from 12 to 45, with an average 
of 26. The total offal count varied from 31 to 162, with an average 
of 74. 

GENERAL CONCLUSIONS ON PATENT FLOURS. 

1. The commercial grades of so-called patent flours ranged from 
35 to 90 per cent. These percentage figures apparently were in¬ 
tended to indicate that a certain percentage of the total flour content 
of the wheat kernel passed into this grade, the remainder being 
employed in other grades. 

2. The average total offal count obtained on all commercial patent 
flours examined was 57. 

3. Patent flours showed a marked variation in the total offal count 
obtained on different samples from various mills. 

4. The limitations and the average counts on bran particles and 
hairs have been briefly summarized in Table 21. 








































































































MICROSCOPICAL EXAMINATION OF FLOUR. 


21 


Table 21. —Limitations and average counts on bran 'particles and hairs for patent flours. 


Commercial grade. 

Bran particles. 

Hairs. 

Variation. 

Average. 

Variation. 

Average. 

Hard-wheat patent. 

13 to 72... 

30 

2 to 45 

18 

Soft-wheat patent. 

19 to 133. 

49 

1 to 34 . 

20 

Blended-wheat patent. 

18 to 83. 

‘ 42 

13 to 40. 

21 







STRAIGHT FLOURS. 

When only one grade of flour is manufactured in the mill, this 
grade is commercially designated as a straight flour, if it contains the 
entire flour content of the wheat that it is possible to mill. It might 
be considered to contain all of the flour that could be obtained from 
the wheat kernel with the exception of a certain percentage of so- 
called low-grade or red dog flour. Such a straight flour naturally 
would contain more of the branny particles from the wheat kernel 
than would a patent flour. The practice of compositing such a flour 
apparently varies in different mills. Tests were made upon a large 
number of straight flours milled from hard, soft, and blended wheats. 
The detailed information on these tests is given in the following para¬ 
graphs. 

STRAIGHT FLOURS MILLED FROM HARD WHEATS. 

Seventeen straight flours reported as having been milled from 
hard wheats were examined for their offal content. The com¬ 
mercial grades ranged from 92 to 100 per cent. The results of the 
examination appear in Table 22. 


Table 22. —Results of examination of straight flours milled from hard wheats. 


Sample No. 

Com¬ 

mercial 

grade. 

Bleached. 

Bran 

particles. 

Hairs. 

Total. 

151 Qfi-'K'-TT . 

“Per cent 
straight” 
92 

No. 

33 

34 

67 

11028-K-E... 

95 

(?). 

71 

55 

126 

17157- L-B .. 

95 

Yes. 

50 

45 

95 

i7155-L-HH . . 

96 

Yes. 

89 

33 

122 

151M-RT-C . 

97 

Yes. 

37 

25 

62 

15106-K . 

97* 

98 

(?). 

57 

39 

96 

11067 K . 

(?). 

62 

31 

93 

15136-K BB .- 

98 

Yes. 

55 

51 

106 

15147-K . 

98 

Yes. 

58 

61 

119 

15191-K . 

98 

(?). 

62 

87 

149 

15194-K-TJ . 

98 

Yes. 

71 

65 

136 

17113 L . 

98 

Yes. 

63 

19 

82 

17152-L-Y ... . 

98 

(?). 

57 

26 

83 

17177-L-XX . 

98 

No. 

71 

47 

118 

11073-K-GG . 

100 

(?)... 

76 

61 

137 

17146-L F . 

100 

No. 

60 

17 

77 

17186-L-F . 

100 

No. 

121 

22 

143 







The count obtained on bran particles ranged from 33 to 121 and 
that on hairs from 17 to 87. The average bran particle count was 
64 and the average hair count 43. The total offal count ranged 
from 62 to 149, with an average of 106. 






































































22 


BULLETIN 839, U. S. DEPARTMENT OF AGRICULTURE. 


STRAIGHT FLOURS MILLED FROM SOFT WHEATS. 

Seventeen straight flours reported to have been milled from soft 
wheats were examined. The commercial grades ranged from 90 
to 100 per cent. Table 23 gives the results of this examination. 

Table 23 .—Results of examination of straight flours milled from soft wheats. 


Sample No. 

Commer¬ 

cial 

grade. 

Bleached. 

Bran 

parti¬ 

cles. 

Hairs. 

Total. 

11096-K. 

“Per cent 
straight.” 
90 

No. 

52 

10 

92 

11097-K. 

90 

Lightlv. 

41 

31 

72 

11098-K. 

90 

Heavily. 

56 

38 

94 

15125-K-BB. 

90 

Yes..... 

92 

58 

150 

15126-K-DllD. 

90 

Yes. 

89 

26 

115 

17166-L-Q. 

90 

Yes. 

50 

60 

110 

15125-K-FF. 


Yes. 

111 

70 

181 

173 

15125-K-J.T. 


No. 

119 

54 

17188-L-X. 

97^ 

No. 

55 

27 

82 

15125-K-Y . 

100 

Yes. 

109 

71 

180 

15125-K-OO. 

100 

Yes. 

153 

81 

234 

15126-K-A A A .. 

100 

Yes. 

93 

40 

133 

17136-L-Z. 

100 

Yes. 

97 

22 

119 

17165-L-AA. 

100 

Yes. 

109 

34 

143 

17176-L-W. 

100 

No. 

52 

39 

91 

17185-L-H. 

100 

No. 

34 

34 

68 

17186-L-C.*.. 

100 

No. 

92 

38 

130 




0 

The bran particle count varied from 34 to 153, with an average of 
82, and the hair count varied from 22 to 81, with an average of 45. 
The total offal count ranged from 68 to 234, with an average of 127. 

STRAIGHT FLOURS MILLED FROM BLENDED WHEATS. 

Eighteen samples of flour stated to have been milled from blends 
of hard and soft wheats were examined for their offal content, as in 
the case of the hard and soft types. The commercial grade desig¬ 
nations varied from 90 to 100 per cent. The results of the exam¬ 
ination are given in Table 24. 

Table 24 .—Results of examination of straight flours milled from blended wheats. 


Sample No. 


11087-K_ 

11088-K_ 

11089-K_ 

17118-L-J... 
17173-L-V.. 
11096-K.... 

11097-K_ 

11098-K_ 

17120-L-N.. 
17121-L-SS.. 

11090-K_ 

11091-K_ 

11092-K_ 

17117-L-DD 
17115-L-E.. 
17173-L-W. 
15195-K-A.. 
17128-L-Z.. 


Commer¬ 

cial 

grade. 

Bleached. 

% 

Bran 

parti¬ 

cles. 

• 

Hairs. 

Total. 

“Per cent 

straight.” 

90 

No. 

50 

26 

76 

90 

Lightly. 

51 

22 

73 

90 

Heavily. 

50 

28 

78 

90 

No. 

183 

18 

201 

90 

Yes. 

21 

36 

57 

90 

No. 

52 

40 

92 

90 

Lightly. 

41 

31 

72 

90 

Heavily. 

56 

38 

94 

96 

Yes. 

90 

47 

137 

97 

No. 

98 

30 

128 

97* 

No. 

42 

28 

70 

97* 

Lightly. 

43 

29 

72 

97* 

Heavily. 

52 

26 

78 

97* 

Yes.. . 

73 

37 

110 

96* 

No. 

83 

45 

128 

98 

No. 

33 

47 

80 

100 

No. 

88 

58 

146 

(?) 

No. 

86 

37 

123 































































































MICROSCOPICAL EXAMINATION OF FLOUR. 


23 


The bran particle count varied from 33 to 183, with an average of 
68, while the hair count varied from 18 to 58, with an average of 34. 
The total offal count varied from 57 to 201, with an average of 100. 
The average total offal count obtained for the straight flours was 111, 
as against 57 for patent flours. 

MILL STREAMS EMPLOYED IN THE MANUFACTURE OF CERTAIN STRAIGHT FLOURS. 

I 

Data were obtained on the mill streams employed in the manu¬ 
facture of certain straight flours, and these streams were examined 
for their offal content for the purpose of illustrating the quality of 
the material sometimes used in making up such flours. The results 
are given in Tables 25, 26, and 27. 


Table 25. —Results of examination of mill streams employed in the manufacture of a 
straight flour (sample No. 17146-L-F) milled from hard wheats. 


Stock. 

Bran 

particles. 

Hairs. 

Totals 

First break. 

186 

83 

269 

Second break. 

166 

65 

231 

Third break. 

367 

144 

511 

Fourth break. 

322 

116 

438 

Fifth break. 

456 

176 

632 

Second middlings. 

29 

2 

31 

Third middlings. 

27 

6 

33 

Third middlings (second stream). 

13 

4 

17 

Fifth middlings. 

21 

5 

26 

Cut-off flour. 

15 

4 

19 

Cut-off flour. 

76 

18 

94 

Chunk flour. 

308 

90 

398 

Second chunk flour. 

50 

5 

55 

Tailings flour... 

76 

24 

100 

Tailings flour. 

155 

47 

202 

100 per cent straight flour 1 . 

60 

17 

77 


i Composited from the mill streams listed above it. 


Table 26. —Results of examination of mill streams employed in the manufacture of a 
straight flour (sample No. 17165-L-AA) milled from soft wheats. 


Stock. 

Bran 

particles. 

Hairs. 

Total. 

First, break. 

113 

38 

151 

Rooond break. 

75 

38 

113 

r Phi rrl lirp.alc _ .... 

131 

53 

184 

irirct ceennrt Anri third breaks. 

101 

45 

146 

*17mirth hrfiftk__-. 

228 

106 

334 

fifth Break . 

368 

173 

541 

"First, mid dlimr.S...... 

21 

8 

29 

Reervnd middlings... 

48 

27 

75 

Third middlings... 

26 

7 

33 

"Fourth middlings.. 

29 

2 

31 

mirifilings. __ .. 

55 

12 

67 

Rivt.h middlings.. .. 

60 

18 

78 

Rovonth midHlinPS... 

143 

23 

166 

*Ri frh f h m i rl rl 1 i n L r s.. 

264 

38 

302 

‘F’lrdt. flprm flour . 

50 

5 

55 

100 -nor Pont straight, flour 1 ... 

109 

34 

143 



1 Composited from the mill streams listed above it. 




















































24 BULLETIN 839, U. S. DEPARTMENT OF AGRICULTURE. 

Table 27 .—Results of examination of mill streams employed in the manufacture of a 
straight flour (sample No. 17128-L-Z ) milled from blended wheats. 


Stock. 


First break.. 

Second break. 

Third break. 

Fourth break. 

Fifth break. 

First middlings.... 
Second middlings.. 
Third middlings... 
Fourth middlings. 
Fifth middlings 
Sixth middlings... 
Seventh middlings 

First sizings. 

Second sizings. 

First tailings. 

Second tailings.... 

Head cuts. 

Tail cuts. 

Straight flour i. 


Bran 

particles. 

Hairs. 

- V - 

Total. 

334 

162 

496 

150 

83 

233 

118 

53 

171 

118 

50 

168 

296 

101 

397 

66 

31 

97 

41 

21 

62 

69 

26 

95 

38 

23 

61 

74 

36 

110 

70 

37 

107 

63 

26 

89 

56 

11 

67 

107 

34 

141 

134 

43 

177 

108 

48 

156 

132 

63 

195 

130 

70 

200 

87 

37 

124 


1 Composited from the mill streams listed above it. 


GENERAL CONCLUSIONS ON STRAIGHT FLOURS. 

1. The commercial grades of so-called straight flours ranged from 
90 to 100 per cent. 

2. The average total offal count obtained on all commercial straight 
flours examined was 111. 

3. Straight flours showed a decided variation in the total offal 
count obtained on different samples from various mill£ 

CLEAR FLOURS. 

Clear flour, so-called, is often considered among millers as being a 
mixture of odds and ends of the milling stocks. Low grades of mid¬ 
dlings and break flours often pass into it, although frequently it con¬ 
tains the purest quality of middlings stock from the tail of the mill. 
Clear flours which were said to have been milled from hard, soft, and 
blended wheats, respectively, were examined. 

CLEAR FLOURS MILLED FROM HARD WHEATS. 


Tliirty-one clear flours stated to have been milled from hard wheats 
were examined. Their percentages ranged from 6 to 52. Table 28 
shows the counts thus obtained. 































MICROSCOPICAL EXAMINATION OF FLOUR 


25 


Table 28. —Results of examination of clear flours milled from hard wheats. 


Sample No. 


17180-L-KK.. 
17151-L-OO.. 
17142-L-EE.. 
17112-L-T.... 
17150-L-U.... 
15138- K-DD.. 

17154-L-CC_ 

17145-L-A.... 
17147-L-AA.. 
17175-L-NN.. 

17183-L-B_ 

17184-L-P 
11065-K-A.... 

11070-K-JJ_ 

11079-K-KK. 
15169-K-DD.. 
15192- K-FF.. 
15186-K-Y — 

11028-K-C_ 

15175-K-MM- 
17143-L-BB.. 
17144-L-II.... 

15115-K. 

15116-K. 

15117-K. 

11071-K-EE.. 

17186-L-E_ 

15150-K-AA.. 
15137-K-FF.. 
15180-K-A A.. 
17151-L-NN.. 


Commer¬ 

cial 

grade. 

Bleached. 

Bran 

particles. 

Hairs. 

Total. 

“Per cent 

clear.” 

6 

Yes.•. 

331 

132 

463 

8 

No. 

238 

166 

404 

10 

No. 

306 

50 

356 

12 

No. 

191 

98 

289 

12 

No. 

197 

77 

274 

13 

No. 

156 

126 

282 

14 

No. 

294 

223 

517 

15 

No. 

181 

102 

283 

15 

No. 

271 

184 

455 

15 

No. 

241 

62 

303 

16 

No. 

193 

136 

329 

16 

No. 

127 

119 

246 

18 

(?). 

65 

39 

104 

22 

No. 

82 

68 

150 

22 

Yes. 

71 

67 

138 

23 

(?). 

131 

124 

255 

23 

Yes. 

410 

196 

606 

24 

No. 

172 

140 

312 

25 

(?). 

193 

204 

397 

25 

(?). 

158 

102 

260 

25 

No. 

316 

71 

387 

26 

No. 

271 

93 

364 

27* 

No. 

92 

71 

163 

27* 

Lightly. 

79 

57 

136 

27* 

Heavily. 

77 

49 

126 

30 

(?). 

127 

178 

305 

30 

No. 

268 

43 

311 

35 

Yes. 

118 

133 

251 

33-35 

(?). 

126 

114 

240 

18 

(?). 

151 

147 

298 

52 

No. 

72 

45 

117 


The bran particle count on these samples varied from 65 to 331, 
with an average of 174. The hair count ranged from 43 to 223, with 
an average of 109. The total offal count varied from 104 to 517, 
with an average of 295. 

CLEAR FLOURS MILLED FROM SOFT WHEATS. 

Thirteen samples of clear flour reported to have been milled from 
soft wheats were examined, these samples varying from 54 to 50 
per cent as far as commercial grades are concerned. Table 29 gives 
the results obtained. 

Table 29. —Results of examination of clear flours milled from soft wheats. 


Sample No. 

Com¬ 

mercial 

grade. 

Bleached. 

Bran 

particles. 

Hairs. 

Total. 

15122-K-AA . 

“Per cent 
clear.” 
5* 
5* 
5* 
20 

Yes. 

243 

155 

398 

15122-K-LL . 

No. 

244 

164 

408 

15126-K-EEE . 

(?). 

282 

99 

381 

17178-Tj—A A S . 

No. 

137 

66 

203 

17132-L-W . 

25 

No. 

308 

30 

338 

15122-K-DD . 

30 

Yes. 

245 

167 

412 

15127—K M\f . 

30 

No. 

208 

143 

351 

17160-L-D . 

30 

Yes. 

235 

44 

279 

17162 T, TT . 

30 

No.... 

160 

40 

200 

1713?? T, EE . 

35 

Yes. 

247 

39 

286 

1 71 fi7 T, or, . 

50 

Yes. 

126 

32 

158 

171SR-T, R . 

50 

No. 

177 

68 

245 

IIOOfi-K . . 

25 

(?). 

253 

72 

325 



























































































































26 BULLETIN 839, U. S. DEPARTMENT OF AGRICULTURE. 

The bran particle count varied from 126 to 308, with an average 
of 218. The hair count ranged from 30 to 167, with an average of 
86. The total offal count ranged from 158 to 412, with an average 
of 306. 

CLEAR FLOURS MILLED FROM BLENDED WHEATS. 

Twelve samples of flour stated to have been milled from blended 
wheats were examined. The commercial grades ranged from 10 to 
30 per cent. Table 30 gives the results of the examination. 

Table 30. —Results of examination of clear flours milled from blended wheats. 


Sample No. 

Com¬ 

mercial 

grade. 

Bleached. 

Bran 

particles. 

Hairs. 

Total. 

17179-L-ZZ. 

“Per cent 
clear. ” 

10 

No. 

115 

61 

176 

17116-L-E. 

15 

No. 

127 

65 

192 

I7123-L-GG. 

15 

No. 

250 

73 

323 

17125-L-GG. 

15 

No. 

297 

40 

337 

17171-L-C... . 

20 

No. 

209 

96 

305 

11093-K. 

27| 

27! 

27! 

30 

No. 

76 

45 

HI 

il094-K. 

Lightly. 

55 

49 

104 

11095-K . 

Heavily. 

61 

47 

108 

17182-L-II. 

No.../.. 

166 

142 

308 

17173-L-Y. 

40 

No. 

- 112 

98 

210 

17172-L-BB. 

50 

Yes. 

88 

44 

132 

17159-L-W. 

25 

No. 

111 

67 

178 




The bran particle count varied from 55 to 297, with an average 
count of 139, and the hair count varied from 40 to 142, with an 
average of 69. The total offal count varied from 104 to 337, with 
an average of 207. 

MILL STREAMS EMPLOYED IN THE MANUFACTURE OF CERTAIN CLEAR FLOURS. 

Tables 31 and 32 record the results obtained on certain mill 
streams which were employed in making up clear flours. As in the 
case of the commercial grades already considered, these figures are 
merely submitted to demonstrate the quality of the stocks that might 
be used in such a flour from the standpoint of offal material. 

Table 31. —Results of examination of mill streams employed in the manufacture of a 
clear flour (sample No. 17143-L-BB) milled from hard wheat. 


Stock. 


First and third breaks. 

Second break. 

Third break. 

Fourth break...^. 

First tailings.. 

Second tailings. 

Third tailings. 

Fourth tailings. 

First germ flour. 

Second germ flour. 

First dustings flour.... 
Third dustings flour... 
Dust collector material 
25 per cent clear flour 1 . 


Bran 

particles. 

Hairs. 

Total. 

310 

59 

369 

324 

42 

366 

628 

107 

735 

810 

213 

1,023 

120 

5 

125 

120 

4 

124 

38 

1 

39 

567 

72 

639 

43a 

38 

468 

560 

• 33 

593 

184 

28 

212 

110 

15 

125 

575 

99 

674 

316 

71 

387 


1 Composited from the mill streams listed above it. 
































































MICROSCOPICAL EXAMINATION OF FLOUR. 27 


Table 32. —Results of examination of mill streams employed in the manufacture of a 
clear flour (sample No. 11079-K-JJ) milled from hard wheat. 


Stock. 

Bran 

particles. 

Hairs. 

Total. 

First break. 

196 

165 

361 

Third break (head). 

120 

121 

241 

Third break (tail).. 

100 

103 

203 

Fifth middlings... 

28 

24 

52 

Sixth middlings (head). 

46 

45 

91 

Sixth middlings (tail). 

55 

26- 

81 

Seventh middlings (head). 

56 

27 

83 

First sizings.. 

87 

31 

118 

First tailings (head). 

151 

58 

209 

First tailings (tail).. 

87 

32 

119 

22 per cent clear flour 1 . 

82 

68 

150 



1 Composited from the mill streams listed above it. 
GENERAL CONCLUSIONS ON CLEAR FLOURS. 


1. The commercial grades of so-called clear flours ranged from 
to 52 per cent. 

2. The average total offal count obtained on all commercial clear 
flours examined was 273. This amount was decidedly in excess of 
the amount obfained on the commercial grades already considered. 

3. As in the case of the other grades, clear flours showed a wide 
variation in the total offal count obtained on products from different 
mills. 

LOW-GRADE FLOURS. 

The low-grade flour is supposed to be made from low-grade mill 
stocks, as might be inferred from the designation applied to this 
class of products. As already stated, the better stocks, for the most 
part, are diverted into the higher grades. The streams entering 
into the composition of the low-grade flours are usually more or less 
specky, due to the presence of offal material. For this reason it is 
quite impossible to obtain an accurate count on such a flour. In 
fact, a casual microscopical examination is usually all that is neces¬ 
sary to determine the quality of the flour. 

LOW-GRADE FLOURS MILLED FROM HARD WHEATS. 

Eleven low-grade flours milled from hard wheats were examined, 
with the results shown in Table 33. The commercial grades ranged 
from 2 to 10 per cent, some of the samples being bleached and others 
unbleached. 


Table 33. —Results of examination of low-grade flours milled from hard wheats. 


Sample No. 

Commer¬ 
cial grade. 

Bleached. 

Bran 

particles. 

Hairs. 

Total. 

li/vifl v . 

“Per cent 
low- 
grade.” 

2 

(?). 

243 

91 

334 

1K11Q XT _..... 

2i 

2y 

2h 

No . 

310 

129 

439 

16119 K . . 

Lightly. v'. - 

340 

131 

471 

1K10A_XV ___ 

Yes . 

310 

112 

422 

IKISfl—TT r> . 

3 

No . 

252 

155 

407 

itns V Y ___ 

2-5 

No . 

175 

88 

263 

11 fien_ IT TTTT ... 

5 

No . 

353 

301 

654 

nncA_F TT . 

5 

Yes . 

274 

335 

609 

11(V)Q_F T> . 

8 

(?). 

269 

264 

533 

ii/v7o v no .. 

6 

(?). 

169 

163 

332 

11080-K-00 . 

10 

Yes . 

317 

238 

555 






























































28 BULLETIN 839, U. S. DEPARTMENT OF AGRICULTURE. 

The bran particle count varied from 169 to 353, with an average 
of 273. The hair count ranged from 88 to 335, with an average of 
182. The total offal count varied from 263 to 654, with an average 
of 456. 

LOW-GRADE FLOURS MILLED FROM SOFT WHEATS. 


The eight samples of low-grade flour milled from soft wheats ranged 
from 2 to 10 per cent, with bleaching being practiced in some instances 
and not in others. Table 34 gives the results of this examination. 


Table 34. —Results of examination of low-grade flours milled from soft wheats. 


Sample No. 

Commer- 

cialgrade. 

Bleached. 

Bran par¬ 
ticles. 

Hairs. 

Total. 

17136-L-Y. 

“ Per cent 
low- 
grade.” 
(?) 
(?) 

2 

(?). 

202 

27 

229 

17185-L-G. 

No. 

143 

257 

400 

17176-L-X. 

No. 

309 

238 

145 

454 

17188-L-W. 

3 

No . 

261 

499 

15123-K-Z. 

41 

41 

6 

Yes. 

402 

219 

621 

15126-K-CCC. 

No. 

390 

307 

139 

529 

17178-L-BBS. 

No. 

124 

431 

17165-L-Y. 

10 

Yes. 

331 

80 

411 




The bran particle count varied from 143 to 402, with an average 
of 302. The hair count ranged from 27 to 261, with an average of 
140. The total offal count varied from 229 to 621, with an average of 
446. 

LOW-GRADE FLOURS MILLED FROM BLENDED WHEATS. 


Eight samples of flour stated to have been milled from blended 
wheats ranged in commercial grades from 1^ to 10 per cent, only one 
sample of the number being represented as having been bleached. 
The results of the examination are shown in Table 35. 


Table' 35. —Results of examination of low-grade flours milled from blended wheats . 


Sample No. 


17123-L-EE.. 

17128-L-T_ 

17117-L-Y- 

17115-L-F_ 

17120-L-J_ 

17171-L-D- 

17172-L-A A.. 
17179-L-AAA 


Commer¬ 
cial grade. 

Bleached. 

Bran par¬ 
ticles. 

Hairs. 

Total. 

“Per cent 
low- 
grade.” 
(?) 

No. 

394 

59 

453 

(?) 

No. 

100 

61 

161 

n 

No. 

211 

76 

287 

3i 

(?). 

357 

141 

498 

4 

No. 

397 

183 

580 

5 

No. 

237 

94 

331 

10 

Yes. 

281 

131 

412 

10 

No. 

262 

132 

394 


The bran particle count had limitations of from 100 to 397, with 
an average of 279. The hair count varied from 59 to 183, with an 
average of 109. The total offal count ranged from 161 to 580. with 
an average count of 389. 






























































MICROSCOPICAL EXAMINATION OF FLOUR. 


29 


GENERAL CONCLUSIONS ON LOW-GRADE FLOURS. 

1. The commercial grades of so-called low-grade flours ranged from 
2 to 10 per cent. 

2. The average total offal count obtained on all commercial low- 
grade flours examined was 433. This indicated that not as much 
attention was given to the purification of the stocks passing into 
such flours as was done in the case of the stocks composing the 
grades already considered. 

3. The data obtained on the low-grade flours milled from the dif¬ 
ferent wheats are summarized in Table 36. 


Table 36. —Limitations and average counts on bran 'particles and hairs for low-grade 

flours. 


Type. 

Bran particles. 

Hairs. 

Variation. 

Average. 

Variation. 

Average. 

Hard wheat. 

169 to 353.... 

273 

88 to 335. 

182 

Soft wheat. 

143 to 402.... 

302 

27 to 261... 

140 

Blended wheat. 

100 to 397.... 

279 

59 to 183... 

109 






EXAMINATION OF EXPERIMENTAL SERIES OF FLOUR. 

In connection with the examination of commercial flours it was 
considered advisable to examine samples of flour whose composition 
was definitely known, as far as the wheat from which they were milled 
and their constituent streams were concerned. The information in 
regard to the commercial samples was definite enough in so far as 
the milling operator was able to judge. 

The samples of flour employed in this part of the investigation were 
milled under the personal supervision of B. C. Winslow, food and 
drug inspector, Bureau of Chemistry, United States Department of 
Agriculture. The samples were prepared at a plant at Lyons, Kans., 
a portion being milled from a No. 2 Nebraska hard winter wheat, crop 
of 1914, containing from 25 to 35 per cent of yellow berry wheat, and 
another portion from a Kansas No. 2 hard winter wheat. Each type 
of flour was subjected to three degrees of bleaching, thus making 
three samples for each type. Four types of flour were made from 
each wheat, a 70 per cent, a 90 per cent, a 97.5 per cent, and a 27.5 
per cent. In the case of the Kansas wheat a fifth type, a 2.5 per cent, 
was made. The component streams that passed into each type and 
the results of the examinations made were as follows: 

THE 70 PER CENT TYPE OF EXPERIMENTAL FLOUR. 

COMPOSITION. 

First sizings flour. Fourth middlings flour. 

Second sizings flour. Fifth middlings flour. 

First middlings flour. Fine tailings flour. 

Second middlings flour. Coarse tailings flour. 

Third middlings flour. 


























30 


BULLETIN 839, U. S. DEPARTMENT OF AGRICULTURE. 


Table 37. —Results of examination of 70 per cent type of experimental flour. 


Wheat. 

Sample number. 

Degree of 
bleaching. 

Bran 

particles. 

Hairs. 

Total. 


(11084-K. 

N one. 

29 

13 

42 

No. 2 Nebraska, hard winter. 

<11085-K. 

Lightlv. 

32 

13 

45 

[11086-K. 

Heavily. 

31 

18 

49 


(15112-K. 

None. 

10 

12 

22 

No. 2 Kansas, hard winter... 

Average count. 

•{15113-K. 

Lightlv. 

12 

9 

21 

[15114-K . 

Heavily. 

( l ) 

22 

C) 

13 

( l ) 

35 


1 Not counted; infested with weevils. - 


THE 90 PER CENT TYPE OF EXPERIMENTAL FLOUR. 

COMPOSITION. 


First sizings flour. 
Second sizings flour. 
First middlings flour. 
Second middlings flour. 
Third middlings flour. 
Fourth middlings flour. 
Fifth middlings flour. 
Fine tailings flour. 
Coarse tailings flour. 


Second break flour. 

Third break flour. 

Fourth break flour. 

Sharp section (middlings). 
Cut-off flour (middlings). 
Sixth middlings flour. 
Seventh middlings flour. 
Eighth middlings flour. 


Table 38. —Results of examination of 90 per cent type experimental flour. 


Wheat. 

Sample number. 

Degree of 
bleaching. 

Bran 

particles. 

Hairs. 

Total. 


111087-K. 

N one. 

50 

26 

76 

No. 2 Nebraska, hard winter. 

<11088-K. 

Lightly. 

51 

22 

73 

(11089-K. 

Heavily. 

50 

28 

78 


115109-K. 

None. 

32 

31 

63 

No. 2 Kansas, hard winter... 

<15110-K. 

Lightly. 

31 

28 

59 


Il5111-K. 

Heavily. 

28 

34 

62 




Average. 



40 

28 

68 





THE 97.5 PER CENT TYPE OF EXPERIMENTAL FLOUR. 

COMPOSITION. 


First sizings flour. 

Second sizings flour. 

First middlings flour.. 
Second middlings flour. 
Third middlings flour. 
Fourth break flour. 

Sharp section (middlings). 
Cut-oft flour (middlings). 
Sixth middlings flour. 
Seventh middlings flour. 


Fourth middlings flour. 
Fifth middlings flour. 
Fine tailings flour. 
Coarse tailings flour. 
Second break flour. 
Third break flour. 
Eighth middlings flour.. 
First break flour. 

Fifth break flour. 

Ninth middlings flour. 
Flour from dust-collecting reels. 


Table 39. —Results of examination of 97.5 per cent type of experimental flour. 


Wheat. 

Sample number. 

Degree of 
bleaching. 

Bran 

particles. 

Hairs. 

Total. 


(11090-K. 

N one. 

42 

28 

70 

72 

78 

96 

72 

58 


11091-K. 

Lightly. 

43 

29 

No. 2 Nebraska, hard winter. 

11092-K. 

Heavily. 

52 

26 

15106-K. 

None..'.. 

57 

39 


15107-K. 

Lightly. 

43 

29 


15108-K. 

Heavily. 

28 

30 




Average. 



44 

30 

74 
























































































MICROSCOPICAL EXAMINATION OF FLOUR. 


31 


THE 27.5 PER CENT TYPE OF EXPERIMENTAL FLOUR. 


Second break flour. 
Third break flour. 
Fourth break flour. 
Sharp section. 


COMPOSITION. 

Cut-off flour (middlings). 
Sixth middlings flour. 
Eighth middlings flour. 
First break flour. 


Fifth break flour. 

Ninth break flour. 

Flour from dust collectors. 
Seventh middlings flour. 


Table 40. —Results of examination of 27.5 per cent type of experimental flour. 


Wheat. 

Sample number. 

Degree of 
bleaching. 

Bran 

particles. 

Hairs. 

Total. 


|11093-K. 

None. 

76 

45 

121 

No. 2 Nebraska, hard winter. 

U1094-K. 

Lightly. 

55 

49 

104 

U1095-K. 

Heavily. 

61 

47 

108 


(15115-K. 

None. 

56 

65 

121 

No. 2 Kansas, hard winter... 

115116-K. 

Lightly. 

49 

51 

100 

(15117-K. 

Heavily. 

51 

40 

91 




Average. 



58 

49 

107 





THE 2.5 PER CENT TYPE OF EXPERIMENTAL FLOUR. 

COMPOSITION. 

Bran duster flour. Shorts duster flour. 

Cut-off flour from seventh middlings. Cut-off flour from ninth middlings. 


Table 41. —Results of examination of 2.5 per cent type of experimental flour. 


Wheat. 

Sample number. 

Degree of 
bleaching. 

Bran 

particles. 

Hairs. 

Total. 

No. 2 Kansas, hard winter... 

Average_ 

115118-K. 

N one. 

310 

340 

310 

129 

131 

112 

439 

471 

422 

<15119-K. 

Lightly. 

[ 15120-K. 

Heavily. 



320 

124 

444 

I 



GENERAL CONCLUSIONS ON EXPERIMENTAL TYPES OF FLOUR. 

The best grade of flour of the experimental series averages a lit¬ 
tle lower in total offal count than the best grade in the commercial 
set, being 57 for the commercial flours and 35 for those of the experi¬ 
mental set. The two intermediate grades of the commercial flours 
were higher in the offal count than similar grades in the experimental 
series, the count being 111 and 273 for the commercial flours and 71 
and 107 for those of the experimental set. Both of the lower-grade 
flours, that from the commercial and experimental sets, respectively, 
compared very favorably as far as the offal count was concerned, 
these figures being essentially minimum ones although approxi¬ 
mately representative of the two products. 

< * 

SUMMARY. 

1. Microscopical technique was devised for the enumeration of 
the offal material in flour of various commercial grades. 

2. The data obtained on the various commercial grades of flour 
demonstrated that there was little uniformity in the matter of grad¬ 
ing finished flours in different mills. 

3. The experimental data submitted have shown a wide range in 
the offal content among flours of the same commercial grade (appar¬ 
ently) produced by different mills. 

4. The information obtained concerning the samples examined 
leads to the inference that all mills do not composite finished flours 
in the same manner. 

















































32 


BULLETIN 839, U. S. DEPARTMENT OF AGRICULTURE. 


5. The microscopical examination of the constituent streams en¬ 
tering into the composition of a finished flour shows the effect of the 
addition of different mill stocks on the resulting offal content. 

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(1) Amos, P. A. 

Processes of Flour Manufacture. 1912. 

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Establish Definite Grades of Flour, Offal, and Stock. The Operative Miller, 
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Beitrage zur Mehluntersuchung. Chem. Ztg., 56:121-123. 1912. 

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Methodes pratiques d’analvses des farines. Rev. intern, fals., 6:133-136, 
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Analyse microscopique des farines. Ann. chim. anal., 77:371-372. 1906. 

(15) Moore, B., and Wilson, J. T. 

The Effects of Nitrogen Peroxide on the Constituents of Flour in Relation to 
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(16) Posner, C. 

Studien zur Mikroskopie von Mehl und Brot. Zeit. Nahr. Genussm., 29: 329- 
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(17) Rammstedt, Otto. 

Die Bestimmung der Farbe des Mehles und das Sichtbarmachen von Klei- 
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Estimation of the Quality of Flour. Ann. Lab. chim. cent. Gabelle., 6:425- 
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Zu Mehluntersuchung. Zeit. Nahr. Genussm., 77:86-88. 1909. 

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The Analysis of Wheat Flour for Commercial Purposes. 

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Microscopic Analysis of Flour and Bread. Staz. sper. agrar. ital., 45:143-150. 
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o • 


























